Please help me! What are some good tips for potty training my 6 month old male black pug puppy?

He's definitely not afraid to use the doggy door and when he does do his business outside he goes behind a tree in our yard. But thats very seldom usually he goes inside and his favorite spot is right beside my bed. I think he's just doing it to bug me!But seriously i want to train him to potty outside behind the tree and try not to go in front of guests if it can be helped.